1. Field of the Invention
The present invention relates to an article transport facility having a movable body configured to travel along a travel rail provided in a transporting space and to transport an article.
2. Description of the Related Art
Article storage facilities such as one described above sometimes have a transporting space which is divided by a wall into a first space and a second space with an opening being formed in the wall for communication between the first space and the second space and with a shutter being provided that can open and close this opening. The shutter is provided to prevent a fire from spreading to the other space when the fire breaks out in either the first space or the second space, or to prevent flow of air between the spaces when the first and second spaces have a different atmospheric environment (that is, the state or condition of the air which fills respective space differs between the spaces).
In order to allow articles to be transported from the first space to the second space and vice versa in an article transport facility with a shutter for opening and closing an opening provided in a wall that divides the transporting space into the first space and the second space as described above, a travel rail is conventionally provided which extends through the opening from the first space to the second space to allow a movable body carrying an article to travel along the travel rail and through the opening to transport articles between the first space and the second space. (See, for example, JP Patent Application Publication No. H06-100163.)
As described in Publication H06-100163, when a travel rail is provided between the first space and the second space as described above, in order for the shutter for opening and closing the opening to close the opening properly, a portion of the travel rail that is located at a position corresponding to the opening-and-closing position of the shutter in the longitudinal direction of the travel rail needs to have a gap for allowing the shutter to pass. And the thickness of the shutter is made thinner than the dimension of this gap so that the opening can be closed properly when the shutter is closed.
In a conventional article transport facility, the travel rail is cut so as to form a gap for allowing the shutter to pass; so, the wheels of the movable body will have to travel over the cut location when the movable body passes the opening. This causes a problem that the cut location of the travel rail and wheels rub against or frictionally engage each other, which generates dust. In particular, when the transporting space is a clean environment such as in a semiconductor manufacturing factory, generation of dust poses a significant problem.
In addition, when the movable body passes the opening, traveling of the wheels of the movable body over the cut location causes vibration in the movable body, which in turn causes the article being transported to vibrate, which may result in undesired change in the attitude of the article or damages to the article. Therefore, in such conventional article transport facility, steps need to be taken to suppress vibration of the article. Furthermore, when vibration occurs in the movable body, this has negative effects on the mechanical parts of the movable body, or on the durability of the entire movable body. Thus, the presence of a cut or a gap in the travel rail is undesirable in this respect.